Skip to main content
19 events
when toggle format what by license comment
S Jul 28, 2023 at 19:40 history bounty ended locallito
S Jul 28, 2023 at 19:40 history notice removed locallito
Jul 28, 2023 at 19:40 vote accept locallito
Jul 28, 2023 at 19:35 vote accept locallito
Jul 28, 2023 at 19:40
Jul 25, 2023 at 11:20 answer added Francesco Polizzi timeline score: 4
S Jul 22, 2023 at 3:53 history bounty started locallito
S Jul 22, 2023 at 3:53 history notice added locallito Improve details
Jul 19, 2023 at 16:01 comment added abx The lines are not even cohomogically equivalent, otherwise that would contradict Totaro's paper. And for a smooth threefold $X$ in $\Bbb{P}^4$, $\operatorname{Pic}(X)=\mathbb{Z} $ so every pair of divisors intersect.
Jul 19, 2023 at 14:49 comment added locallito @abx oh, Im curious about that... some reference or example? That lines are linearly equivalent or something else? Is the same true for 3-folds in P^4 for example? That is something that I did not consider.
Jul 19, 2023 at 13:57 comment added abx locallito: of course not! A smooth surface of degree $d$ in $\Bbb{P}^3$ is of general type as soon as $d\geq 5$ (and not ruled as soon as $d\geq 3$).
Jul 19, 2023 at 13:36 comment added locallito @JasonStarr oh! That is just to introduce the topic. Precisely Im asking for "non-trivial" examples where the meaning of "non-trivial" is written above.
Jul 19, 2023 at 13:33 comment added locallito @abx Is not that a ruled surface?
Jul 19, 2023 at 10:17 comment added Jason Starr To the OP: please clarify what you are asking about. Presumably those authors explain what they mean by "asymptotically many" disjoint divisors (perhaps bigger than the second Betti number, or some other number defined in terms of invariants of the variety). However, the MO community does not know what you mean by "asymptotically many" disjoint divisors.
Jul 19, 2023 at 4:16 comment added abx A smooth surface in $\Bbb{P}^3$ can contain many disjoint lines.
Jul 19, 2023 at 3:57 history edited locallito CC BY-SA 4.0
added 22 characters in body
Jul 18, 2023 at 23:37 history edited locallito CC BY-SA 4.0
added 33 characters in body
Jul 18, 2023 at 23:29 history edited locallito CC BY-SA 4.0
added 40 characters in body
S Jul 18, 2023 at 23:14 review First questions
Jul 19, 2023 at 1:43
S Jul 18, 2023 at 23:14 history asked locallito CC BY-SA 4.0